多重耐药临床菌株中整合子结构的检测与分析

目的研究广州暨南大学附属第一医院2004年部分临床菌株样本的整合子及其基因盒的分布特性。方法多重PCR检测与细菌耐药关系密切的1、2、3类整合酶基因,进一步对阳性样本可变区的基因盒序列鉴定分析。结果随机抽取109株临床菌株,整合酶阳性检出率为97.2%(106/109),其中1类整合酶阳性菌100株(91.7%),2类整合酶阳性菌1株(0.92%),此外有5株(4.6%)同时检出1、2类整合酶,没有检测到3类整合酶;基因盒鉴定结果显示,插入基因盒以dfrA(甲氧苄氨嘧啶耐药相关)和aadA(氨基糖苷类耐药相关)基因家族为主,也在少数菌株中发现了aacA4、cmlA1、catB3以及sat1基因盒。其中又以dfrA12、orfF和aadA2组合最为常见,耐药基因盒PCR扩增片段为1913bp(64.6%);此外,还发现了同时存在两种整合子结构的菌株。结论整合子普遍存在于临床菌株中,可通过基因水平转移在不同菌属间传播,提示各医药单位必须加强耐药监测及合理选择抗菌药物,以减少多重耐药细菌的发生和发展。

Detection and characterization of integron structure in clinical bacteria isolates

Objective To investigate the distribution,characterization and relativity between multi-(resistance) and integrons.Methods In this study,the presence and genetic content of 3 classes integrons(among) 109 clinical strains were examined by multiple PCR and sequencing.Restricted enzyme-fragment length polymorphisms(RFLP) was also used for the homology of the gene cassettes.Results intI1 was detected in 91.7% of the isolates;intI2 was detected in 1(0.92%) isolates,both intI1 and intI2 were detected in other 5(4.6%) isolates and no intI3 was detected.Twelve different genes,including 10 genes respondible for antibiotic resistance and 2 unknown genes,were detected.The genes most commonly found in integrons were those for aminoglycoside(aadA) and trimethoprim(dfr) resistance.Bacteria contain more than one integron were also found in this study.Conclusion Resistance mediated by integron was extensively existed in clinical isolates of both Gram-negative and Gram-positive bacteria.It seems that the integrons are more widely existed than we expected.It implied the necessary for surveillance horizontal transference of antibiotic resistance gene(s)(among) bacteria genus.